FIG. 1 shows the typical structure of a portion of a liquid crystal display device. The basic structural elements of a liquid crystal cell 1 for use in a liquid crystal display device are a back light (not shown) provided on the back side of the display panel, a TFT substrate 220, a color filter substrate 100, and a liquid crystal 210 sandwiched between the TFT substrate 220 and the color filter substrate 100. The TFT substrate 220 comprises a transparent glass substrate 5, a polarizer (not shown), a transistor 6 for controlling pixels formed on the transparent glass substrate 5, gate scan lines 7-1, storage capacitor lines 7-2 and a transparent electrode having an orientation film on the uppermost layer. On the other hand, the basic structural elements of the color filter substrate 100 are a transparent substrate 2, a color filter 3 and a common electrode formed on the transparent substrate 2. Cylindrical spacers 4-2 are formed at non-transparent portions where the black matrices of the color filter substrate are positioned between the color filter substrate 100 and the TFT substrate 220 in order to make the thickness of the space for the liquid crystal uniform throughout the screen.
The light from the back light is linearly polarized by a polarizing plate (not shown) provided on the TFT substrate, the polarization properties are controlled (i.e., the polarization is changed or remains unchanged) during passage through the liquid crystal 210), and the light is blocked or transmitted by the polarizing plate provided on the color filter substrate 100.
Liquid crystal display devices having such a structure are described in JP2003-233064A, JP2000-305086A and so on. FIG. 2 schematically shows the typical structural elements of the color filter substrate in a liquid crystal display device. The display screen is composed of a plurality of pixels each having color filters for red (R) 3-1, blue (B) 3-2 and green (G) 3-3. The spacers 4-2 are formed on the black matrices 4-1 by exposure of a photosensitive resin and an etching process. Additionally, the spacers 4-2 have a height of approximately 4 μm, and are formed to the same height so as to prevent any unevenness in the color where the liquid crystal is filled.
During the process of manufacturing color filter substrates, they are coated with color ink to a thickness of 1-3 μm. However, during the process of laying ink on the pixels of the color filters, protrusions 8 can be formed on the filter pixel portions, depending on the physical parameters such as the viscosity and rate of setting of the color ink. These are protruding defects, having a height 10 of approximately 10 μm and a cylinder diameter of 20-100 μm.
When these protruding defects occur, the distance between the color filter substrate and the TFT substrate positioned opposite thereto may be determined by the height 10 of the protrusions 8 which are defects, instead of the height 9 of the spacers 4-2. As a result, the thickness of the space for the liquid crystal can differ depending on the position, causing the colors to be uneven and making the liquid crystal display cells defective.
According to publicly known art, when protrusions are formed on color filters, protruding defects identified by inspection are irradiated with a pulse laser to remove the entire protrusions, including dust and color ink forming the protrusions, down to the transparent substrate, recesses are formed in the surrounding color filters, then these orifices are filled with correcting ink using a dispenser, to thereby correct defects due to contaminant protrusions (Patent Document 3). A method involving removal of contaminants on the color filter using a UV laser, coating with a black resist at positions where there is color loss, and setting by UV irradiation.    Patent Document 1: JP2003-233064A    Patent Document 2: JP2000-305086A    Patent Document 3: JP2003-279722A    Patent Document 4: JP2003-57428A